1. Field of the Invention
The present invention relates to the technical field of a lens barrel and an imaging apparatus, particularly the technological field in which a biasing spring presses a pressing roller supported by a first moving frame against a second moving frame to prevent a group of lenses from being inclined to the optical axis so as to improve, for example, optical performance.
2. Description of the Related Art
Some imaging apparatuses, such as a still camera and a video camera, include a lens barrel having a plurality of groups of lenses movable in the optical axis direction for focusing and zooming.
Examples of such lens barrels include a lens barrel assembled as part of the imaging apparatus to the apparatus body in advance, and a removable lens barrel attached to the apparatus body, a so-called exchangeable lens.
In recent years, imaging apparatuses tend to be smaller in body size and larger in pixel size. Being smaller in body size and larger in pixel size makes the impact of lens manufacturing error on image quality larger, resulting in the problem of increased difficulty in manufacturing.
To address the problem, two groups of lenses having opposite sensitivities are secured in a lens holder to form a movable unit in an imaging apparatus of related art. Even when the movable unit is inclined to the optical axis, the errors of the two groups of lenses are cancelled because they have opposite sensitivities, thus reducing the impact on the image quality and the difficulty in manufacturing.
However, when such two groups of lenses form a movable unit, each of the groups of lenses is not independently moved in the optical axis direction. The design specifications, such as the zoom magnification, become restricted, resulting in the problem of a smaller degree of design freedom.
To solve such two problems of an increased difficulty in manufacture and a smaller degree of design freedom, there is an imaging apparatus capable of moving a movable unit in the optical axis direction with the movable unit pressed against a predetermined member (see JP-A-2000-266981, for example).
In the imaging apparatus described in JP-A-2000-266981, which is configured in such a way that the movable unit having a group of lenses is moved in the optical axis direction when a cam barrel rotates relative to the stationary barrel, a rotation output member that exerts a rotary drive force on the cam barrel is biased in a direction perpendicular to the optical axis so as to press the cam barrel against the stationary barrel.
In such a configuration, the cam barrel pressed against the stationary barrel prevents the group of lenses provided in the movable unit from being inclined to the optical axis, so that the difficulty in manufacturing can be reduced and the rotation of the cam barrel can move a plurality of movable units independently, resulting in an improvement in the degree of design freedom.